Notwithstanding the minimum twenty-five (25') foot front yard setback requirement for this zone district, an open roofed porch of a single-family dwelling may extend into the required front yard setback a maximum of six (6') feet. The front yard setback of the open roofed porch shall not be less than nineteen (19') feet. The open roofed porch extending into the front yard setback shall not contain walls or coverings, only open railings. This exception shall only apply to the first story features.